Germany international midfielder Marcell Jansen is a doubt for this summer's World Cup due to an ankle injury.
The 24-year-old suffered ligament damage in training on Friday that could require surgery.
Jansen has suffered from a string of injuries in the past two seasons, but had hoped to be fit for South Africa this summer.
The former Bayern Munich man has bemoaned the timing of the injury with the Bundesliga season entering a crucial stage.
"Such an injury at this time of the season is a hard blow because we're going to play some important games and because the World Cup in South Africa is a big objective," he told the Hamburg's official website.